Field of the Invention
The present invention relates to a method with which it is possible to detect whether an attempt is made at manipulatory intervention in a chip card or smart card.
Because chip cards should be reliable during regular use and, unauthorized use of the card must be detected, there is the problem that it is difficult to set a practical level of sensitivity for a system for protecting against attempts at intervention. A sensory protection system is intended to ensure that abnormal operating states that can be exploited during an attempt at intervention are sensed and attempts at manipulatory interventions are themselves detected. If the sensors are set at too sensitive a level so that they respond even when there are small deviations from the normal state, they also react to unavoidable small fluctuations in the operating conditions. As a result, the reliability of the respective product is, under certain circumstances, greatly restricted, for example even slight short-term current fluctuations in a card reader lead to a reset of the controller. For this reason it is necessary to make compromises in the setting of the sensitivity of such protection sensors.